Peptide Binding Glucose Regulated Protein 78 Improves Type 1 Diabetes by Preventing Pancreatic ß Cell Apoptosis.

BACKGROUND AND OBJECTIVES: Diabetes Type 1 is characterized by hyperglycemia due to reduced insulin secretion that results from the death of pancreatic ß cells. It was suggested that endoplasmic reticulum (ER) stress is associated with the autoimmune-mediated ß cell destruction. Glucose regulated protein 78 (GRP78) functions as a key regulator to maintain the ER function. Under stress conditions GRP78 is up-regulated and expressed on the cell surface serving as a signaling receptor. Our first objective was to examine the effects of peptide binding cell surface GRP78 to reduce the deleterious effects of diabetes induced by streptozotocin. The second objective was to demonstrate the ability of the peptide to protect the pancreatic ß cells from apoptosis. METHODS: The effect of ADoPep on weight loss, HbA1c levels and anti GRP78 antibody titers was evaluated in a diabetes mouse model. The effect of ADoPep on the pancreatic ß Ins1E cell apoptosis was determined by FACS analysis. RESULTS: The administration of ADoPep to diabetic mice retained the weight loss and reduced HbA1c significantly in 60% of mice. Titers of anti GRP78 antibodies increased in 70% of the treated mice. Apoptosis was significantly inhibited in stressed pancreatic ß Ins 1E cells. CONCLUSIONS: We demonstrate that administration of the peptide ADoPep to diabetic mice improved type 1 diabetes by preventing pancreatic ß cell apoptosis.

Effect of High Dose Statin Pretreatment on Endothelial Progenitor Cells After Percutaneous Coronary Intervention (HIPOCRATES Study).

BACKGROUND: Pretreatment with high-dose statins given before percutaneous coronary intervention (PCI) has been shown to have beneficial effects, in particular by reducing peri-procedural myocardial infarction. The mechanism of these lipid-independent beneficial statin effects is unclear. Circulating endothelial progenitor cells (EPCs) have an important role in the process of vascular repair, by promoting re-endothelization following injury. We hypothesized that statins can limit the extent of endothelial injury induced by PCI and promote re-endothelization by a positive effect on EPCs. We, therefore, aimed to examine the effect of high-dose statins given prior to PCI on EPCs profile. METHODS: Included were patients, either statin naïve or treated chronically with low-dose statins, with stable or unstable angina who underwent PCI. Patients were randomized to receive either high-dose atorvastatin (80 mg the day before PCI and 40 mg 2-4 h before PCI) or low- dose statin. EPCs profile was examined before PCI and 24 h after it. Circulating EPCs levels were assessed by flow cytometry as the proportion of peripheral mononuclear cells co-expressing VEGFR-2+ CD133+ and VEGFR-2+ CD34+. The capacity of the cells to form colony forming units (CFUs) was quantified after 7 days of culture. RESULTS: Twenty three patients (mean age 61.4 ± 7.4 years, 87.0% men) were included in the study, of which 12 received high-dose atorvastatin prior to PCI. The mean number of EPC-CFUs before PCI was higher in patients treated with high-dose atorvastatin vs. low-dose statins (165.8 ± 58.8 vs. 111.7 ± 38.2 CFUs/plate, respectively, p < 0.001). However, 24 h after the PCI, the number of EPC-CFUs was similar (188.0 ± 85.3 vs. 192.9 ± 66.5 CFUs/plate in patients treated with high-dose atorvastatin vs. low- dose statins, respectively, p = 0.15). There were no statistical significant differences in FACS analyses between the 2 groups. CONCLUSIONS: The current study showed higher EPC- CFUs levels in patients treated with high-dose atorvastatin before PCI and a lower increment in EPC-CFUs after PCI. These findings could account for the beneficial effects of statins given prior to PCI, yet further investigation is required.

Effect of nesiritide in patients with acute decompensated heart failure.

BACKGROUND: Nesiritide is approved in the United States for early relief of dyspnea in patients with acute heart failure. Previous meta-analyses have raised questions regarding renal toxicity and the mortality associated with this agent. METHODS: We randomly assigned 7141 patients who were hospitalized with acute heart failure to receive either nesiritide or placebo for 24 to 168 hours in addition to standard care. Coprimary end points were the change in dyspnea at 6 and 24 hours, as measured on a 7-point Likert scale, and the composite end point of rehospitalization for heart failure or death within 30 days. RESULTS: Patients randomly assigned to nesiritide, as compared with those assigned to placebo, more frequently reported markedly or moderately improved dyspnea at 6 hours (44.5% vs. 42.1%, P=0.03) and 24 hours (68.2% vs. 66.1%, P=0.007), but the prespecified level for significance (P≤0.005 for both assessments or P≤0.0025 for either) was not met. The rate of rehospitalization for heart failure or death from any cause within 30 days was 9.4% in the nesiritide group versus 10.1% in the placebo group (absolute difference, -0.7 percentage points; 95% confidence interval [CI], -2.1 to 0.7; P=0.31). There were no significant differences in rates of death from any cause at 30 days (3.6% with nesiritide vs. 4.0% with placebo; absolute difference, -0.4 percentage points; 95% CI, -1.3 to 0.5) or rates of worsening renal function, defined by more than a 25% decrease in the estimated glomerular filtration rate (31.4% vs. 29.5%; odds ratio, 1.09; 95% CI, 0.98 to 1.21; P=0.11). CONCLUSIONS: Nesiritide was not associated with an increase or a decrease in the rate of death and rehospitalization and had a small, nonsignificant effect on dyspnea when used in combination with other therapies. It was not associated with a worsening of renal function, but it was associated with an increase in rates of hypotension. On the basis of these results, nesiritide cannot be recommended for routine use in the broad population of patients with acute heart failure. (Funded by Scios; ClinicalTrials.gov number, NCT00475852.).

Angiogenic peptides improve blood flow and promote capillary growth in a diabetic and ischaemic mouse model.

OBJECTIVES: It is a common clinical observation that collateral vessel development is impaired in diabetic patients with ischaemic vascular diseases. Consequently, alternative revascularisation strategies in diabetic patients are needed. This study presents the effect and mechanism of new peptide therapeutic angiogenesis in an ischaemic and diabetic mouse model. DESIGN: Streptozocin-injected mice that had undergone hind-limb ischaemia were treated with angiogenic peptides. Blood flow restoration was calculated by laser Doppler imager and corroborated by histological section. For the mechanism study, endothelial cells were exposed to hypoxia and high glucose concentrations to study the effect of the peptides on proliferation and anti-apoptosis. RESULTS: The peptides significantly restored blood perfusion 21 days after surgery in the diabetic mice (p < 0.01) by neo-vascularisation, corroborated by an increase in capillary density. In addition, the peptides induced the proliferation of hypoxic endothelial cells (p < 0.01) and protected the cells from apoptosis in high glucose cultures. CONCLUSIONS: This is the first approach for treatment of ischaemic vascular disease with peptides in a diabetic mouse model.

Junctional rhythm quantity and duration during slow pathway radiofrequency ablation in patients with atrioventricular nodal re-entry supraventricular tachycardia.

AIM: The occurrence of accelerated junctional rhythm during radiofrequency energy delivery at the region of the slow pathway is a well-recognized marker of successful treatment of atrioventricular nodal re-entry tachycardia (AVNRT). Our aim was to evaluate if the quantity and duration of accelerated junctional rhythm during radiofrequency ablation of the slow pathway is correlated with residual slow pathway conduction. METHODS AND RESULTS: Forty consecutive patients with AVNRT undergoing radiofrequency ablation of slow pathway who developed accelerated junctional rhythm during ablation were included. We compared accelerated junctional rhythm quantity and duration between two groups: group A, without echo beats and group B, with echo beats on post-ablation electrophysiology study. The total amount of accelerated junctional rhythm was significantly greater in group A than in group B [75.0 (63.5-165.0) vs. 36.0 (24.0-65.0), P=0.006], as well as total duration of accelerated junctional rhythm [47.0(33.5-81.0) s vs. 23.0 (16.0-42.0) s, P=0.006]. The cycle length of accelerated junctional rhythm did not differ between the two groups [510.0 (445.0-545.0) ms vs. 500.0 (450.0-585.0) ms, P=0.5). CONCLUSIONS: The amount and duration of accelerated junctional rhythm is correlated with the total abolishment abolition of slow pathway conduction. A higher amount and duration of accelerated junctional rhythm during radiofrequency applications may be an additional marker of successful ablation.

Are neutrons involved in the pathogenesis of life-threatening cardiac arrhythmias?

Geomagnetic fields protect the earth from the adverse effects of cosmic rays, whose activity can be indirectly measured by monitoring the level of neutrons in the environment. The number and days of discharges from automatic implantable cardioverter defibrillators (ICD) in patients with cardiac arrhythmias are inversely correlated with the daily level of geomagnetic activity (GMA). The aim of the present was to determine whether neutron levels on days of AICD discharges are higher than average. Days on which discharges occurred were recorded in 31 patients bearing ICDs for managing ischemic cardiomyopathy. Daily neutron levels obtained from the monitoring data of the Russian Academy of Sciences in Moscow were analyzed using Student's t test. The mean (+/-SD) daily neutron level for the 1096-day period was 8299.29 +/- 294.236 imp/min (median 8252), and for days of ACID discharge, 8423.93 +/- 274.187 imp/min (median 8443) (p = 0.0002). The mean neutron activity on days of AICD discharges in response to ventricular disturbances was significantly higher than the mean level over the 1096-day study period. Whether this relation is a direct result of low GMA or due to an independent role of neutrons in the pathogenesis and timing of cardiac arrhythmias is unknown.

Which factors are associated with the application of reperfusion therapy in ST-elevation acute coronary syndromes?. Lessons from the Euro Heart Survey on Acute Coronary Syndromes I.

BACKGROUND/AIMS: A large proportion of patients with a ST-elevation acute coronary syndrome do not receive reperfusion therapy. In order to contribute to a better understanding of the clinical decision making process, we analyzed which factors are associated with the application of reperfusion therapy. METHODS: From the Euro Heart Survey of Acute Coronary Syndromes I, 4,260 patients with ST-elevation acute coronary syndrome were selected for the current analysis, of which 1,539 (36%) patients received fibrinolysis and 904 (21%) primary percutaneous coronary intervention (PCI). The analysis contained 32 variables on demographics, medical history, admission parameters and reperfusion therapy. RESULTS: A short pre-hospital delay, arrival in a hospital with PCI facilities, severe ST-elevation, and participation in a clinical trial were the strongest predictors for receiving reperfusion therapy. Primary PCI was more likely to be performed than fibrinolysis in patients with a long pre-hospital delay, arriving in a hospital with PCI facilities, not participating in a clinical trial, and with at least one previous PCI. CONCLUSION: Hospital facilities and culture, pre-hospital delay and infarction size play a major role in management decisions regarding reperfusion therapy in ST-elevation acute coronary syndrome. This analysis indicates which factors require special attention when implementing and reviewing the reperfusion guidelines.

Diabetes mellitus: clinical presentation and outcome in men and women with acute coronary syndromes. Data from the Euro Heart Survey ACS.

AIMS: To study clinical presentation, in-hospital course and short-term prognosis in men and women with diabetes mellitus and acute coronary syndromes (ACS). METHODS: Men (n = 6488, 21.2% with diabetes) and 2809 women (28.7% with diabetes) < or = 80 years old, with a discharge diagnosis of ACS were prospectively enrolled in the Euro Heart Survey of ACS. RESULTS: Women with diabetes were more likely to present with ST elevation than non-diabetic women, a difference that became more marked after adjustment for differences in smoking, hypertension, obesity, medication and prior disease [adjusted odds ratio (OR) 1.46 (1.20, 1.78)], whereas there was little difference between diabetic and non-diabetic men [adjusted OR 0.99 (0.86, 1.14)]. In addition, women with diabetes were more likely to develop Q-wave myocardial infarction (MI) than non-diabetic women [adjusted OR 1.61 (1.30, 1.99)], while there was no difference between men with and without diabetes [adjusted OR 0.99 (0.85, 1.15)]. There were significant interactions between sex, diabetes and presenting with ST-elevation ACS (P < 0.001), and Q-wave MI (P < 0.001), respectively. Of the women with diabetes, 7.4% died in hospital, compared with 3.6% of non-diabetic women [adjusted OR 2.13 (1.39, 3.26)], whereas corresponding mortality rates in men with and without diabetes were 4.1% and 3.3%, respectively [OR 1.13 (0.76, 1.67)] (P for diabetes-sex interaction 0.021). CONCLUSION: In women with ACS, diabetes is associated with higher risk of presenting with ST-elevation ACS, developing Q-wave MI, and of in-hospital mortality, whereas in men with ACS diabetes is not significantly associated with increased risk of either. These findings suggest a differential effect of diabetes on the pathophysiology of ACS based on the patient's sex.

Cardiovascular risk factors and clinical presentation in acute coronary syndromes.

OBJECTIVE: To investigate the hypothesis that risk factors may be differently related to severity of acute coronary syndromes (ACS), with ST elevation used as a marker of severe ACS. DESIGN: Cross sectional study of patients with ACS. SETTING: 103 hospitals in 25 countries in Europe and the Mediterranean basin. PATIENTS: 10,253 patients with a discharge diagnosis of ACS in the Euro heart survey of ACS. MAIN OUTCOME MEASURES: Presenting with ST elevation ACS. RESULTS: Patients with ACS who were smokers had an increased risk to present with ST elevation (age adjusted odds ratio (OR) 1.84, 95% confidence interval (CI) 1.67 to 2.02). Hypertension (OR 0.65, 95% CI 0.60 to 0.70) and high body mass index (BMI) (p for trend 0.0005) were associated with less ST elevation ACS. Diabetes mellitus was also associated with less ST elevation, but only among men. Prior disease (infarction, chronic angina, revascularisation) and treatment with aspirin, beta blockers, or statins before admission were also associated with less ST elevation. After adjustment for age, sex, prior disease, and prior medication, smoking was still significantly associated with increased risk of ST elevation (OR 1.53, 95% CI 1.38 to 1.69), whereas hypertension was associated with reduced risk (OR 0.75, 95% CI 0.69 to 0.82). Obesity (BMI > 30 kg/m2 versus < 25 kg/m2) was independently associated with less risk of presenting with ST elevation among women, but not among men. CONCLUSION: Among patients with ACS, presenting with ST elevation is strongly associated with smoking, whereas hypertension and high BMI (in women) are associated with less ST elevation, independently of prior disease and medication.

Initial clinical experience with a hand-held device (Thrombocheck) for the detection of bileaflet prosthetic valve malfunction.

BACKGROUND AND AIM OF THE STUDY: Early recognition of subclinical prosthetic valve malfunction may promote early treatment and avoidance of serious complications. Echocardiography cannot be applied on a daily basis; thus, a hand-held device (Thrombocheck) which is capable of detecting subtle changes in the acoustic sounds of prosthetic valve has been developed for the routine home monitoring of heart valve function. Herein is reported the authors' initial clinical experience with this device. METHODS: Seventy-one consecutive patients with one or more bileaflet prosthetic mechanical valves at any position were assessed both by transthoracic echocardiography (TTE) and by Thrombocheck. These patients attended the authors' clinic for either routine echocardiography (n = 62) or for the detection of prosthetic valve malfunction (n = 9). Cinefluoroscopy and transesophageal echocardiography were used selectively to confirm prosthetic valve malfunction. The Thrombocheck was held for 1 min in the subxiphoid position perpendicular to the patient, and indicated either normal function (OK), abnormal function (Warning) or 'no signal'. RESULTS: The study patients had in total 82 bileaflet valves (47 mitral, 31 aortic, four tricuspid). Eight patients (11.3%) had a 'no signal' indication. Of the remaining 63 patients, 10 (15.9%) had a 'warning' alarm (eight patients had current abnormal leaflet motion, one patient had a recent history of abnormal leaflet motion, and one had no evidence of prosthetic valve malfunction). The sensitivity and specificity for detecting abnormal prosthetic valve malfunction were 90% and 98%, respectively. CONCLUSION: The Thrombocheck had an excellent sensitivity and specificity for the detection of prosthetic valve malfunction in a cohort of patients with bileaflet mechanical prosthetic heart valves.

[Out-of-hospital resuscitation in Israel 2000].

The aim of the study was to evaluate the impact of pre-hospital cardio-pulmonary resuscitation, performed by mobile intensive cardiac care units of Magen David Adom (MDA) teams in the framework of a national survey conducted in the period February and March 2000. During the survey, MDA performed 539 resuscitations, 485 of which were performed by mobile intensive care units of MDA, and they constitute the study population of the present analysis. The average age of the patients was 70.5 years, and 68% were men. The mean response time of the mobile intensive care units was 10.3 minutes. In 14% of the cases, a bystander initiated basic cardiac life support before the arrival of the MDA team. Upon arrival of the resuscitation team, 242 patients (50%) had asystole, 19% ventricular tachycardia (VT)/ventricular fibrillation (VF), 13% pulseless electrical activity (PEA), and 18% had other severe arrhythmias. One hundred and ninety-nine patients (41%) were transferred alive to the hospital after successful resuscitation. Hospital summaries were obtained for 148 of these patients. The cause of cardiac arrest was cardiac in 64% of the cases and 48% of the patients who reached the hospital had a previous history of heart disease. Fifty-three patients (11%) were discharged alive from the hospital. Patients discharged alive were younger, more promptly resuscitated, 78% had a cardiac cause of death and 38% of them were in ventricular tachycardia/fibrillation when first seen by the resuscitation team. The rate of successful resuscitation to discharge in the sub-group with VT/VF was 21%, and only 4% for patients in asystole, which is in line with other studies. However, the rate of initiation of resuscitation by bystanders is low in Israel. These data may help the medical staff and the health policy providers in Israel.

The safety and efficacy of repeated courses of tissue-type plasminogen activator in patients with stuck mitral valves who did not fully respond to the initial thrombolytic course.

In carefully selected patients with stuck mitral valves, thrombolytic therapy is becoming an established therapeutic modality. However, the management of patient with a suboptimal response to an initial thrombolytic course is unclear. The objective was to evaluate the efficacy and safety of re-administration of tissue-type plasminogen activator (rt-PA) in patients with stuck mitral valves in whom the first thrombolytic course has failed to restore normal prosthetic valve function. The study group included patients who received rt-PA and did achieve a full restoration of valve function after the initial course. Data were gathered on the safety and success rates of additional thrombolytic courses in the same hospitalization period, and their predictors. Twelve patients with stuck mitral valves experienced a total of 13 episodes in which a full resolution of leaflet abnormality was not achieved after the initial thrombolytic course. A repeated thrombolytic course was attempted in 10 patients (11 episodes). Six patients (60%) showed full success rate with repeated thrombolysis, one (10%) showed partial success, and three patients (30%) had no improvement following the second course. These last three were those with initial failure. Age, gender, valve model, worst functional class, time since valve implantation and International Normalized Ratio (INR) levels were similar in both groups. No major adverse events were noted. In this small group of patients with stuck mitral valves, re-administration of rt-PA after a partial response to an initial thrombolytic course was effective and safe. However, total failure of the first thrombolytic course predicted inefficiency of further courses.

Improved prognosis of patients presenting with clinical markers of spontaneous reperfusion during acute myocardial infarction.

OBJECTIVE: To describe the clinical features, management, and prognosis of patients presenting with clinical markers of spontaneous reperfusion (SR) during acute myocardial infarction (AMI). DESIGN: Cohort study. SETTING: National registry of 26 coronary care units. PATIENTS: 2382 consecutive patients with AMI. MAIN OUTCOME MEASURES: Patient characteristics, management, and mortality. RESULTS: The incidence of SR was 4% of patients (n = 98) compared with thrombolytic treatment (n = 1163, 49%), primary angioplasty (n = 102, 4%), and non-reperfusion (n = 1019, 43%). SR patients were more likely to develop less or no myocardial damage as indicated by a higher percentage of non-Q wave AMI (58% v 32%, 47%, and 44%, respectively, p < 0.0001), aborted AMI (25% v 9%, 8%, and 12%, p < 0.001), and lower peak creatine kinase (503 v 1384, 1519, and 751 IU, p < 0.0001). SR patients, however, were more likely to develop recurrent ischaemic events (35% v 17%, 12%, and 16%, respectively; p < 0.001) and subsequently were more likely to be referred to coronary angiography (67%), angioplasty (41%), or bypass surgery (16%, p < 0.001). Mortality at 30 days (1% v 8%, 7%, and 13%, respectively, p < 0.0001) and one year (6% v 11%, 12%, and 19%, p < 0.0001) was significantly lower for SR patients than for the other subgroups. By multivariate analysis, SR remained a strong determinant of 30 day survival (odds ratio (OR) 0.16, 95% confidence interval (CI) 0.01 to 0.74). At one year, the association between SR and survival decreased (OR 0.49, 95% CI 0.18 to 1.13). CONCLUSIONS: Clinical markers of SR are associated with greater myocardial salvage and favourable prognosis. The vulnerability of SR patients to recurrent ischaemic events suggests that they need close surveillance and may benefit from early intervention.

A prospective survey of the characteristics, treatments and outcomes of patients with acute coronary syndromes in Europe and the Mediterranean basin; the Euro Heart Survey of Acute Coronary Syndromes (Euro Heart Survey ACS).

AIMS: To better delineate the characteristics, treatments, and outcomes of patients with acute coronary syndromes (ACS) in representative countries across Europe and the Mediterranean basin, and to examine adherence to current guidelines. METHODS AND RESULTS: We performed a prospective survey (103 hospitals, 25 countries) of 10484 patients with a discharge diagnosis of acute coronary syndromes. The initial diagnosis was ST elevation ACS in 42.3%, non-ST elevation ACS in 51.2%, and undetermined electrocardiogram ACS in 6.5%. The discharge diagnosis was Q wave myocardial infarction in 32.8%, non-Q wave myocardial infarction in 25.3%, and unstable angina in 41.9%. The use of aspirin, beta-blockers, angiotensin converting enzyme inhibitors, and heparins for patients with ST elevation ACS were 93.0%, 77.8%, 62.1%, and 86.8%, respectively, with corresponding rates of 88.5%, 76.6%, 55.8%, and 83.9% for non-ST elevation ACS patients. Coronary angiography, percutaneous coronary interventions, and coronary bypass surgery were performed in 56.3%, 40.4%, and 3.4% of ST elevation ACS patients, respectively, with corresponding rates of 52.0%, 25.4%, and 5.4% for non-ST elevation ACS patients. Among patients with ST elevation ACS, 55.8% received reperfusion treatment; 35.1% fibrinolytic therapy and 20.7% primary percutaneous coronary interventions. The in-hospital mortality of patients with ST elevation ACS was 7.0%, for non-ST elevation ACS 2.4%, and for undetermined electrocardiogram ACS 11.8%. At 30 days, mortality was 8.4%, 3.5%, and 13.3%, respectively. CONCLUSIONS: This survey demonstrates the discordance between existing guidelines for ACS and current practice across a broad region in Europe and the Mediterranean basin and more extensively reflects the outcomes of ACS in real practice in this region.

Comparison of primary coronary angioplasty versus thrombolysis in patients with ST-segment elevation acute myocardial infarction and grade II and grade III myocardial ischemia on the enrollment electrocardiogram.

We investigated the impact of primary angioplasty compared with thrombolysis in 894 patients with ST elevation acute myocardial infarction and electrocardiographic grades II and III ischemia on enrollment. Patients were divided into 2 groups based on the enrollment electrocardiogram-grade III: (1) absence of an S wave below the isoelectric baseline in leads that usually have a terminal S configuration (leads V(1) to V(3)), or (2) ST J-point amplitude > or =50% of the R-wave amplitude in all other leads. To be included in the grade III group, grade III criteria in > or =2 adjacent leads were required. Patients with ST elevation but without grade III criteria were classified as having grade II. In-hospital mortality was 3.2% and 6.8% in the grade II (n = 616) and grade III (n = 278) groups, respectively (p = 0.016). In the grade II group, in-hospital mortality was similar in the thrombolysis and angioplasty subgroups (3.2% and 3.3%, p = 0.941). In patients with grade III, in-hospital mortality was 6.4% and 7.3%, respectively (p = 0.762). The odds ratio for the grade III group for death with thrombolysis was 2.06 (95% confidence intervals [CI] 0.82 to 5.19; p = 0.125); the odds ratio for primary angioplasty was 2.30 (95% CI 0.93 to 5.66; p = 0.07). In the thrombolysis group, reinfarction occurred in 3.3% and 6.5% of the grade II and grade III subgroups (p = 0.137). In the angioplasty group, reinfarction occurred in 1.3% and 4.4%, respectively (p = 0.239). Grade III ischemia on admission was associated with higher in-hospital and 30-day mortality and a higher rate of reinfarction. There was no difference in mortality between primary angioplasty and thrombolysis in the grade II and grade III ischemia patients.

The effects of streptokinase and hydroxyethyl starch on in vitro clot disruption by ultrasound.

BACKGROUND: In vitro studies showed that low-frequency ultrasound (US) causes blood clot dissolution. This effect is augmented with thrombolytics, microbubbles and microparticles. However, in animal models of transcutaneous delivery, US alone is not effective, probably due to attenuation of US energy by overlying skin. When combined with thrombolytics or microbubbles, transcutaneous US is highly effective. PURPOSE: To assess the synergistic effect of low-intensity low-frequency US and saline, hydroxyethyl starch (HAES) (a non-gas filled microparticle containing solution), streptokinase (STK), and their combination on blood clot disruption. METHODS: Human blood clots from 4 healthy donors, 2-4 hours old, were immersed for 0, 15, or 30 min in 37 degrees C in 10 ml of the above-mentioned solutions, and then were randomized to 10 sec of 20 kHz US or no US. The % difference in weight was calculated. RESULTS: Immersion for 30 min without US resulted in 13.8 +/- 1.2% clot lysis in saline, and 22.0 +/- 1.3%, 21.7 +/- 2.1%, and 23.2 +/- 1.9% in STK, HAES, and STK + HAES, respectively (p = 0.002). US augmented clot lysis in all groups and at all time points. With low-intensity US, HAES was not better than saline. However, the combination of HAES + STK with US resulted in larger clot disruption at 15 sec incubation time (46.7 +/- 3.2%) than with saline (29.6 +/- 2.1%), HAES (29.6 +/- 2.5%), and STK (32.8 +/- 3.6%) (p < 0.001). CONCLUSION: low-frequency, low-intensity US combined with HAES and STK resulted in greater clot disruption at short incubation times. This combination may assist in achieving faster reperfusion in in vivo models.